Synthetic routes to alpha-methylene lactones with possible tumor-inhibitory properties will be examined. Model systems will be used to develop efficient reaction sequences for the basic structural features of natural tumor inhibitors. Classes of compounds include elemanolides, germacranolides, pseudoguaianolides, and cembranolides. A variety of approaches including olefin cyclization, fragmentation and stereocontrolled solvolysis, and thermal rearrangement are envisioned.